I have some suggestions for The Sims 5:
I think it'd be awesome to have cross-platform, actual open world and online, where you can use the arrow keys to freely move your Sim(s) around...with your online friends! Everyone can still create their households in CAS, build houses, basically everything from The Sims 3—no loading screens, open world, cars, etc.
But wouldn't it be awesome to use the arrow keys to and whatnot to freely move yourself around as a Sim and drive around town with your online friend(s) joining you in your car? Get the whole crew together and actually be able to go inside a grocery store, actually pick up things from shelves, go to the self-checkout, ring your stuff up, "accidentally forget" to scan the last item and leave the store with your friends and another online person is portraying as the cop who sees you shoplifting and they stop you and arrest you and you actually go to jail?
You could also make yourself take your cell phone out and call your friend but really it would be like a party chat with you and your online friend but it shows your Sim and their Sim on their cell phones, and when you meet up with them, you're in regular open world game chat and anyone who's online can hear you and talk to you using their headsets.
Basically it would be like GTA5 or Red Dead Redemption 2... you have the open world and online/"multiplayer" feature. When you first load into the game, it shows your Sim waking up and getting out of bed and you actually make yourself do stuff. Flip the light switch, cook food, clean stuff, etc. Maybe even add a VR option if players want to really make it look and feel realistic.
See/hear someone online acting a fool? Use the up arrow key and approach him! Put him in his place! Voice chat in open world, still be able to click on people and perform interactions (imply mother is a llama, etc.)